Light-activated tooth whitening method

ABSTRACT

A method of whitening teeth comprises the steps of contacting a stained tooth surface with an organic metal-ligand complex and an oxidizing compound, and exposing the stained tooth surface to actinic radiation.

The present application claims priority from provisional ApplicationSer. Nos. 60/074,708, filed Feb. 13, 1998 and 60/075,222, filed Feb. 19,1998, the contents of which are hereby incorporated by reference intothe present disclosure.

BACKGROUND OF THE INVENTION

This invention relates to improvements in tooth whitening compositionsand methods of using same. In particular, the invention provides noveltooth whitening compositions and methods that use light energy toachieve a faster and improved level of tooth whitening.

White teeth have long been considered cosmetically desirable.Unfortunately, due to the presence of chromogenic (color-causing)substances in food, beverages, tobacco, and salivary fluid, in additionto internal sources such as blood, amalgam restoratives, and antibioticssuch as tetracycline, teeth become almost invariably discolored in theabsence of intervention. The tooth structures that are generallyresponsible for presenting a stained appearance are enamel, dentin, andthe acquired pellicle. Tooth enamel is predominantly formed frominorganic material, mostly in the form of hydroxyapatite crystals, andfurther contains approximately 5% organic material primarily in the formof collagen. In contrast, dentin is composed of about 20% proteinincluding collagen, the balance consisting of inorganic material,predominantly hydroxyapatite crystals, similar to that found in enamel.The acquired pellicle is a proteinaceous layer on the surface of toothenamel which reforms rapidly after an intensive tooth cleaning.

A tooth stain classification system, termed the N (Nathoo)Classification System, has been proposed (J. of the Amer. Dental Asso.,Vol. 128, Special Supplement, April 1997). One form of direct dentalstain is the N1 type stain which occurs when a chromogenic materialbinds to the tooth surface to cause discoloration similar in color tothat of the unbound chromogen Another type of direct dental stain is theN2 type stain, in which a chromogenic material binds to the toothsurfaceand subsequently undergoes a color change after binding to the tooth.Finally, an N3 stain is an indirect dental stain, caused by the bindingof a colorless material (prechromogen) to the tooth, said prechromogenundergoing a chemical reaction that converts it into a chromogen thatcauses tooth stain. Tooth stains may be either extrinsic or intrinsic,depending upon their location within the tooth structure. For example,extrinsic staining of the acquired pellicle arises as a result ofcompounds such as tannins and other polyphenolic compounds which becometrapped in and tightly bound to the proteinaceous layer on the surfaceof the teeth. This type of staining can usually be removed by mechanicalmethods of tooth cleaning that remove all or part of the acquiredpellicle together with the associated stain. In contrast, intrinsicstaining occurs when chromogens or prechromogens penetrate the enameland dentin and become tightly bound to the tooth structure. Intrinsicstaining may also arise from systemic sources of chromogens orprechromogens, for instance, when excess fluoride intake during enameldevelopment leads to the mottled yellow or brown spots typical offluorosis staining. Intrinsic staining is not amenable to mechanicalmethods of tooth cleaning and generally requires the use of chemicals,such as hydrogen peroxide, that can penetrate into the tooth structure,in order to affect a change in the light absorptivity of the chromogen.Intrinsic tooth staining is generally more intractable and difficult toremove than extrinsic tooth staining.

Consequently, tooth-bleaching compositions generally full into twocategories: (1) gels, pastes, or liquids, including toothpastes that aremechanically agitated at the stained tooth surface in order to affecttooth stain removal through abrasive erosion of stained acquiredpellicle; and (2) gels, pastes, or liquids that accomplish thetooth-bleaching effect by a chemical process while in contact with thestained tooth surface for a specified period, after which theformulation is removed. In some cases, an auxiliary chemical process oradditive, which may be oxidative or enzymatic, supplements themechanical process.

Among the chemical strategies available for removing or destroying toothstains, the most effective compositions contain an oxidizing agent, suchas hydrogen peroxide, in order to attack the chromogen molecules in sucha way as to render them colorless, water-soluble, or both. In one of themost popular approaches to whitening a patient's teeth, a dentalprofessional will construct a custom-made tooth-bleaching tray for thepatient from an impression made of the patient's dentition and prescribethe use of an oxidizing gel to be dispensed into the tooth-bleachingtray and worn intermittently over a period of time ranging from about 2weeks to about 6 months, depending upon the severity of tooth staining.These oxidizing compositions, usually packaged in small plasticsyringes, are dispensed directly by the patient, into the custom-madetooth-bleaching tray, held in place in the mouth for contact times ofgreater than about 60 minutes, and sometimes as long as 8 to 12 hours.The slow rate of bleaching is in large part the consequence of the verynature of formulations that are developed to maintain stability of theoxidizing composition. The most commonly used oxidative compositionscontain the hydrogen peroxide precursor carbamide peroxide which ismixed with an anhydrous or low-water content, hygroscopic viscouscarrier containing glycerin and/or propylene glycol and/or polyethyleneglycol. When contacted by water, carbamide peroxide dissociates intourea and hydrogen peroxide. Associated with the slow rate of bleachingin the hygroscopic carrier, the currently available tooth-bleachingcompositions cause tooth sensitization in over 50% of patients. Toothsensitivity is believed to result from the movement of fluid through thedential tubules, which is sensed by nerve endings in the tooth. Thecarriers for the carbamide peroxide enhance this movement. In fact, ithas been determined that glycerin, propylene glycol and polyethyleneglycol can each give rise to varying amounts of tooth sensitivityfollowing exposure of the teeth to heat, cold, overly sweet substances,and other causative agents.

Prolonged exposure of teeth to bleaching compositions, as practiced atpresent, has a number of adverse effects in addition to that of toothsensitivity. These include: solubilization of calcium from the enamellayer at a pH less than 5.5 with associated demineralization;penetration of the intact enamel and dentin by the bleaching agents, soas to reach the pulp chamber of a vital tooth thereby risking damage topulpal tissue; and dilution of the bleaching compositions with salivaresulting in leaching from the dental tray and subsequent ingestion.

Alternatively, there are oxidizing compositions (generally those withrelatively high concentrations of oxidizers) which are applied directlyto the tooth surface of a patient in a dental office setting under thesupervision of a dentist or dental hygienist. Theoretically, such toothwhitening strategies have the advantage of yielding faster results andbetter overall patient satisfaction; however, due to the highconcentration of oxidising agents contained in these so called“in-office” compositions, they can be hazardous to the patient andpractitioner alike if not handled with care. The patient's soft tissues(the gingiva, lips, and other mucosal surfaces) must first be isolatedfrom potential exposure to the active oxidizing agent by the use of aperforated rubber sheet (known as a rubber dam), through which only theteeth protrude. Alternatively, the soft tissue may be isolated from theoxidizers to be used in the whitening process by covering said softtissue with a polymerizable composition that is shaped to conform to thegingival contours and subsequently cured by exposure to a high intensitylight source. Once the soft tissue has been isolated and protected, thepractitioner may apply the oxidizing agent directly onto the stainedtooth surfaces for a specified period of time or until a sufficientchange in tooth color has occurred. Typical results obtained through theuse of a in-office tooth whitener, with or without activation by heat,range from about 2 to 3 shades (as measured with the VITA® Shade Guide,VITA® Zahnfarbik, Bad Saclingen, Germany).

The range of tooth shades in the VITA® Shade Guide varies from verylight (B1) to very dark (C4). A total of 16 tooth shades constitute theentire range of colors between these two endpoints on a scale ofbrightness. Patient satisfaction with a tooth whitening procedureincreases with the number of tooth shade changes achieved. Typically,the minimum generally accepted change is about 4 to 5 VITA® shades.

Attempts have been made to activate peroxides with heat and/or light forthe purpose of whitening teeth. U.S. Pat. No. 4,661,070 discloses amethod of whitening stained teeth which includes the application of aconcentrated solution of hydrogen peroxide within the pulp chamber orupon the surface of a discolored tooth, followed by exposing thediscolored tooth to optical energy consisting of both ultraviolet andinfrared light. The preferred wavelengths of light disclosed by thispatent are from 320 to 420 nanometers and from 700 to 1200 nanometers,with light in the visible spectrum (wavelengths from 500 and 700nanometers) being suppressed. The disclosed method suffers from twoserious drawbacks: (1) ultraviolet light can be hazardous to the patientand practitioner alike and (2) infrared light may cause irreversiblepulpitis if not handled with care.

These drawbacks are partially addressed in U.S. Pat. No. 4,952,143 whichdiscloses a dental bleaching instrument which filters out ultravioletlight and has a temperature regulation mechanism. This patent alsodiscloses the use of visible light with wavelengths ranging from 450 to500 and 650 to 750 nanometers to produce a dark reddish/purple beamwhich facilitates the aiming and focusing of the instrument.

U.S. Pat. No. 5,032,178 discloses compositions and methods to improvedtooth whitening efficacy which uses exposure to “optical energy”,preferably in the visible spectrum wavelength range of 400 to 700nanometers. The compositions disclosed in this patent require the use of(1) an inert silica gelling agent, (2) a catalytic accelerator (eithermanganese sulfate monohydrate or ferrous sulfate), (3) an agent forproviding thixoplasticity and thickening properties to the composition,such as cellulose ethers and methyl vinyl ethers, and (4) a means forindicating completion of the bleaching treatment of the teeth,comprising a redox color indicator for transforming from one color toanother in response to the dissociation of hydrogen peroxide over agiven time period. Compositions described therein are mixedhomogeneously prior to use and all of the required components, includingthe catalyst, are dispersed evenly throughout the mixture. Thecompositions described are not highly transparent to light energy in therange of 400 to 700 nm, due to the presence of the high levels ofinorganic silica particles. Commercial mixtures based on this patent(available under the trade name Shofu Hi-Lite® from Shofu DentalCorporation, Menlo Park, Calif.) confirm that these preparations are nottransparent to visible light, but rather are quite opaque. Typicalresults obtained using such compositions and methods are about 2 to 3VITA® shades improvement in tooth color, similar to that achieved withcompositions that do not employ light energy in the process of bleachingteeth.

U.S. Pat. No. 5,240,415 discloses a dental bleaching system comprising amulti-component kit, one of the required components of said kit beingfumed silica. As described above, silica renders an aqueous compositionrelatively opaque to visible light energy. Again, a tooth shadeimprovement of about 2 to 3 VITA® shades can be expected through the useof this type of composition.

A commercial product called Opalescence Xtra available for bleachingteeth in the controlled environment of a dental office has recently beenintroduced by Ultradent Products, Inc, South Jordan, Utah. This productis believed to be based on the disclosure of U.S. Pat. No. 5,785,527.The commercial product is supplied in a plastic syringe and is describedin the accompanying literature as a light-activated tooth whitening gel,which contains approximately 35% hydrogen peroxide. A pH determinationshowed the product to have a neat pH at 25° C. of about 4.0. The productis thickened to a loose, gel-like consistency with a polymer.Additionally, the product as sold, and as disclosed in U.S. Pat. No.5,785,527, contains a bright orange pigment or dye (carotene), whichpresumably serves as the “photosensitizer”. The manufacturer also claimsthat the photosensitizer is able to absorb light energy and convert itinto heat energy, thereby increasing the activity of the peroxide as atooth bleaching agent. The presence of a photoabsorber in theaforementioned composition renders it relatively opaque to wavelengthsfrom about 400 to 700 nm. Exposure of this composition to light energybetween 400 and 700 nm results in a gradual fading of the orange color,presumably due to a photobleaching effect in the presence of thehydrogen peroxide. Comparative clinical results show an improvement intooth color of from about 3 to 4 VITA® shades, which is highly dependentupon the contact time of the composition on the tooth surface, ratherthan any particular light or heat activation regimen. In addition, thelow pH of the commercial product may cause a reduction in themicrohardness of tooth enamel, due to the dissolution of hydroxyapatitecrystals (which can occur at a pH of around 5:5 or less).

Devices for use in light/heat-activated tooth whitening proceduresinclude the commercially available Union Broach Illuminator. System,from Union Broach, a Health\Chem Company, New York, N.Y. This device, asdescribed by the manufacturer, provides direct, full spectrumillumination to all of the teeth found in the front of the averageadult's mouth. However, this device does not uniformly illuminate allsixteen central teeth in the front upper and lower arches because of thecurvature of the dentition. This potentially gives rise to unevenresults. In addition, the Union Broach device generates a great deal ofheat which is both uncomfortable for the patient and potentiallydamaging to the teeth.

There is thus a need for improved compositions, methods and devices forwhitening teeth that overcome the limitations of the prior art describedabove. In particular, there is a need for tooth whitening compositionsand methods capable of whitening teeth quickly and safely, without harmto tooth enamel, dentin, or pulp. The compositions and methods of thepresent invention described herein satisfy these and other needs.

It is an object of this invention to provide fast and safe toothwhitening compositions and methods that can be activated or acceleratedby the use of light energy.

It is a further object of this invention to provide a tooth whiteningcomposition that shortens the treatment time required to obtain a givenlevel of tooth whitening that is satisfactory to both the patient andthe dentist.

It is another object of the present invention to provide tooth whiteningcompositions that are relatively transparent to light energy in thewavelength range at which tooth chromogens absorb in order to allowexposure of the tooth enamel surface to said light energy while incontact with said tooth whitening compositions.

It is yet another object of this invention to provide compositions andmethods for whitening teeth whereby the extent of tooth whitening, inaddition to the types of tooth stains removed, can be controlled by theduration, intensity and wavelength of actinic radiation exposure at thetooth surface.

SUMMARY OF THE INVENTION

The present invention encompasses methods for whitening teeth, wherein astained tooth surface is contacted with (i) a tooth whiteningcomposition that is transparent to photoactive light and (ii) aphotosensitive agent that is responsive to the wavelengths of light thatare transmitted through the whitening composition and, after contactingwith the composition and agent, the tooth is exposed to a biologicallysafe and effective level of photoactinic light in order to enhance theability of the oxidizing compound in the whitening composition to effectrapid tooth whitening.

Also disclosed and contemplated within the scope of this invention aremethods for whitening teeth, wherein a stained tooth surface iscontacted with an oxidizing compound that is transparent to thewavelengths of light that are absorbed by tooth stain chromogens, andthen exposing the treated tooth to a biologically safe and effectivelevel of those same wavelengths of light in order to effect rapid toothwhitening.

Also disclosed and contemplated within the scope of this invention arethe compositions and compounds described above and devices for whiteningteeth, wherein a minimum of eight central teeth in both the upper andlower arches in an adult are simultaneously and uniformly illuminatedwith a biologically safe and effective level of actinic light to effectrapid tooth whitening.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: A diagram of a device for illuminating the eight central teethin both the upper and lower arches of an adult for use in alight-activated tooth whitening procedure.

FIG. 2: A diagram illustrating the position of two devices forilluminating the eight central teeth in both the upper and lower archesof an adult for use in a light-activated tooth whitening procedure.

FIG. 3: Graph of Comparative Spectra FIG. 4: Spectral Curves of LightAttenuation

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This section details the preferred embodiments of the subject invention.These embodiments are set forth to illustrate the invention, but are notto be construed as limiting. Since the present disclosure is directed tothose skilled in the art field and is not primer on the manufacture oftooth whitening compositions or their use or on devices for using suchcompositions, basic concepts and standard features known to thoseskilled in the art are not set forth in detail. Details for conceptssuch as choosing appropriate construction materials or ingredients,operating conditions or manufacturing techniques, etc. are known orreadily determinable to those skilled in the art. Attention is directedto the appropriate texts and references known to those skilled in theart for details regarding these and other concepts which may be requiredin the practice of the invention; see, for example, Kirk-OthmerEncyclopedia of Chemical Technology, 4th Edition, Volumes 4 (1992), 13(1995), 18 (1996), John Wiley & Sons, NY; Goldstein and Garber, CompleteDental Bleaching, Quintessence Publishing Co. 1995; and theaforementioned Journal of the American Dental Association, Vol. 128,Special Supplement, April 1997, the disclosures of which are herebyincorporated by reference into the present disclosure to aid in thepractice of the invention. The development of the inventive compositionsand methods described herein resulted from the unexpected discovery thatextremely rapid tooth whitening occurs by allowing actinic radiation topenetrate through the oxidizing compound, which is placed directly ontothe tooth surface to be whitened. This discovery is antithetical to allprior art compositions that include a light (or heat) absorbing additivedispersed directly in and homogeneously throughout the oxidizingcompound. The inventive compositions, on the other hand, allow actinicradiation to reach the stained tooth surface at higher power densitiesthan prior art compositions that are specifically designed to absorblight. Actinic radiation is thus more effectively utilized compared toprior art compositions and methods in which compositions are both opaqueto most wavelengths of light and are activated directly by the actinicradiation. As the greatest oxidizing activity is required in the fewmillimeters of enamel and dentin at the tooth surface, the presentinventive compositions and methods are more effective at removing toothstains, in many cases with lower levels of active oxidizing agents,thereby resulting in safer compositions for use in the oral cavity.

For the purpose of this disclosure, the term actinic radiation shallmean light energy capable of being absorbed by either an exogenousphotosensitizing agent or an indigenous tooth chromogen. Also for thepurpose of this disclosure, photosensitizing actinic radiation will meanlight absorbed by a specific photosensitive agent, where aschromosensitizng actinic radiation will mean light absorbed by one ormore tooth chromogens. The terms “actinic radiation” and “actinic light”will be referred to interchangeably.

Also for the purposes of this disclosure, the term “transparent” shallmean having greater than 70% transmission of light at a specifiedwavelength or within a wavelength range. In addition, all compositioningredient percentages are by weight unless otherwise stated.

Various modes of application of the inventive tooth bleachingcompositions are effective, although methods that allow for theaccumulation or concentration of the photosensitizer within the acquiredpellicle, enamel, and dentin (the three tooth structure primarilyassociated with the majority of tooth staining) are most preferred. Thisis best accomplished by contacting the stained tooth surface with thephotosensitizer prior to contacting the same stained tooth surface withthe oxidizing composition. In this way, the photosensitizer is able topenetrate into the tooth structure, thus being present at the site ofthe tooth chromogen(s) prior to contact with the oxidizing compositionand prior to exposure to the actinic radiation source.

Photosensitizing agents useful in accomplishing the desired toothwhitening effect include any compounds capable of absorbing light energyat biologically acceptable wavelengths prescribed by the limits ofsafety for use in the oral cavity. In general, such wavelengths are fromabout 350 nanometers (nm) to about 700 mm, encompassing a portion of theUVA spectrum (300 to 400 nm) and most of the visible light spectrum (400to 700 nm). Examples of compounds which may convert light energy toeither heat of chemical energy, include semiconductor particlesparticularly nanometer-scale titanium dioxide and zinc oxide),benzophenone derivatives, benzotriazole derivatives, diketones (such ascamphorquinone and benzil), metal-ligand complexes (such as ferricpotassium oxalate, manganese gluconate, and various metal—bisphosphonatechelates), phthalocyanin-metal complexes, and others. A specific exampleof a suitable photosensitizing composition is an aqueous dispersion ofzinc oxide with particle sizes between 5 and 20 nanometers. Any moleculecapable of absorbing a photon of light in the wavelength range of fromabout 350 nm to about 700 nm and subsequently converting the energy insaid photon of light into the useful energy of oxidation either alone orin the presence of an auxilliary oxidizing agent, is contemplated tohave utility in the practice of the present invention.

It is preferred that the inventive photosensitizers are of a molecularsize, charge, pH and hydrophobicity/hydrophilicity to allow foreffective penetration into the deeper structures of enamel and dentin.The more readily a photosensitizer penetrates the tooth structure, themore likely that, upon exposure of the photosensitizer to actinicradiation at the appropriate wavelength and energy, said energy will beconverted into oxidative activity at the site of, or in close proximityto, the chromogen itself. Photosensitizers having a molecular size, netcharge, pH, and/or a hydrophobicity/hydrophilicity which prevent orlimit penetration into deeper tooth structures are of utility in thepractice of the present invention, but may be limited to the removaland/or destruction of chromogens located at the outer tooth surface(extrinsic stains).

Especially preferred photosensitizers belong to the general class ofwater-soluble metal-ligand complexes which absorb light in the range offrom about 350 nm to about 700 nm. For the purposes of the presentdisclosure, the term “ligand” will me an an organic molecule capable ofcomplexing or associating with a metal ion in aqueous solution, suchthat the reactivity, solubility, or any other physical property of saidmetal ion is changed. Such metal-ligand complexes are also known asmetal-coordination complexes. Suitable metals ions include iron,manganese, copper, and other transition metal ions. Various valencestates may be used or may be present simultaneously. The metal ions maybe present in saliva, plaque, or the acquired pellicle on the toothsurface. Metal ions may also contribute, through formation of oxides, tocertain types of tooth stains. Suitable metal, ion ligands includechelating agents capable of associating with the metal ions above inaqueous solution, resulting in a water-soluble metal-chelate complexthat absorbs light between about 350 and 700 nm. Illustrative, but by nomeans limiting, examples of metal-coordination complexes are formed fromthe association of iron, manganese and copper with chelators such asethylenediamine tetraacetic acid (EDTA), diethylenetriamine pentaaceticacid (DETPA), nitrilotriacetic acid (NTA),1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), and polyols such as sorbitol, xylitol,mannitol, maltitol, lactitol and other non-carboxylated polyhydroxycompounds more fully described in EP 443,651, such description beingincorporated herein by reference. Any organic multidentate chelatingagent capable of forming a photoabsorbing coordination complex with ametal ion can be presumed to have utility in the present inventivecompositions for and methods of whitening stained teeth.

A number of the inventive metal-ligand complexes have an absorptionspectrum that is pH-dependent; in general, such complexes will display agreater degree of absorption between 350 and 700 nm at a pH of greaterthan about 4.0, light absorption in this range increasing withincreasing pH. For instance, the aqueous complex formed between1-hydroxyethylidene-1,1-diphosphonic acid and ferrous ions is virtuallytransparent to visible light at pH 3.0, but absorbs strongly in thespectral region between 350 and 500 nm as the pH is raised to 7.0.

In some cases, a photosensitizer precursor may be included directlywithin the oxidizing composition, where it does not readily absorb lightin the visible region of the spectrum from 400 to 70 nm. However, uponcontact with the tooth surface (when placed there with the oxidizingcomposition), the photosensitizer precursor may combine, for instance,with a metal ion such as iron present in saliva or found in theinterstitial fluid of enamel and dentin, resulting in the formation, insitu, of an active photosensitizer capable of activating the oxidizingcompound upon exposure to actinic radiation. Obviously, only thosecompounds that are stable in a highly oxidative environment are suitablefor inclusion directly in the oxidizing composition. An example of sucha compound is 1-hydroxyethylidene-1,1-diphosphonic acid (availablecommercially under the trade name Dequest 2010 and sold as a 60% activesolution by Monsanto Corporation, St. Louis, Mo.).

The ability of certain metal chelates to act as photosensitizers hasbeen noted in the literature by various workers. For example, Van derZee, et al (“Hydroxyl Radical Generation by a Light-Dependent FentonReaction” in Free Radical Biology & Medicine, Vol. 14, pp 105-113, 1993)described the light-mediated conversion of Fe (III) to Fe (II) in thepresence of a chelating agent and hydrogen peroxide. The reduction of Fe(III) chelates by light at 300 nanometers to yield Fe (II) was shown toproceed steadily over a period of about 30 minutes, with conversions toFe (II) ranging from about 40% to about 80%, depending upon theparticular chelating compound studied. The Fe (II) thus createdinitiated a Fenton-type degradation of the hydrogen peroxide, yieldinghydroxyl radicals that were spin-trapped and detected by electron spinresonance (ESR). It was not suggested or implied by the authors thatthis photochemical reaction would have utility in the oxidation ofchromophores, such as those found in a human tooth.

Useful oxidizing compounds include liquids and gels, preferablycontaining a peroxide or peroxyacid known in the art. Such oxidizingcompounds include, but are not limited to, hydrogen peroxide, carbamideperoxide, alkali metal peroxides, alkali metal percarbonates, and alkalimetal perborates. Often, it may be desirable to utilize a peroxyacidcompound, such as peroxyacetic acid (for instance, when attempting toeliminate highly intractable tooth stains caused by tetracycline) in thetooth whitening composition. The peroxyacid may be included directlywithin the oxidizing composition (providing that transparency to lightenergy between about 350 and about 700 nanometers is maintained).Alternatively, the peroxyacid may be formed by combining two or moreseparate phases (one of which contains a peroxyacid precursor, such asglyceryl triacetate and a second that contains one of the oxidizingcompounds listed above) prior to application to the tooth surface.Preferably, the peroxyacid is formed in situ, by contacting the toothsurface with a peroxyacid precursor prior to the application of anoxidizing compound; the peroxyacid is thus formed only on and within thestained tooth structure, where it is most beneficial to the toothwhitening process. Suitable peroxyacid precursors include, but are notlimited to, glyceryl triacetate, acetylated amino acids, acetylsalicylicacid, and N,N′-tetraacetyl ethylenediamine, vinyl acetate polymers andcopolymers, acetylcholine, and other biologically acceptable acetylatedcompounds.

The oxidizing compounds are liquid, gel, or solid compositionstransparent to the wavelength(s) of light capable of activating thephotosensitizing agent at the tooth surface; light energy otherwise willbe attenuated by the film or layer of oxidizing compound between theactinic radiation source and the photosensitizer at the tooth enamelsurface. As the tooth enamel surface is the location of the toothdiscoloration, the most effective method of whitening teeth will occurwhen most or all of the light energy reaches the photosensitizer at thetooth enamel surface. An example of a suitable composition that istransparent to light energy between 380 and 500 nm is a 6% hydrogenperoxide gel with a pH of about 7.0 that has been thickened toapproximately 100,000 cps with neutralized carboxypolymethylene.

Another unexpected benefit of utilizing an oxidizing compositiontransparent to photosensitizing actinic radiation is that certainwavelengths of light seem to be absorbed by tooth chromogens in a mannerthat promotes their oxidation to a non-chromogenic state. Reflectancestudies show that dentin and enamel transmit green light, reflectyellow/red light and absorb blue light. Although not wishing to be boundby any particular theory, light is absorbed by the molecules responsiblefor tooth discoloration; thus, tooth chromogens may act in a mannersimilar to that of photosensitizers. In particular, exposure to certainwavelengths may raise the energy state level of pi electrons carbonyl(C═O), double bond (C═C) and conjugated double bond (C═C—C═C) moieties,making them more susceptible to attack by active oxidizing species suchas perhydroxyl anion (HOO—), peroxyacid anions (RCOOO—), and radicalspecies such as hydroxyl radical (HO*) and perhydroxyl radical (HOO*).In order to destroy or solubilize chromogenic substances, the activationenergy of the reaction between one of the above light-absorbing moietiesand an active oxidizing species must be overcome; thus, light assistedchromogen attack leads to more efficient destruction of the molecularmoieties responsible for the appearance of tooth discoloration byraising the energy state of electrons in specific chemical bonds withina light-absorbing molecule from a normal pi bonding orbital to a piantibonding orbital. Whilst in the less stable pi antibonding orbital, alight absorbing double bond has considerable single bond character andis much more easily attacked by oxidizing agents such as peroxides andperoxyacids. In theory, actinic light of a specific energy andwavelength, simply through the process described above, may utilize atooth chromogen molecule as a photosensitizer in order to improve theefficacy of a given oxidative composition in contact with said toothchromogen.

A light-activated tooth whitening method, in accordance with a specificembodiment of the invention includes contacting the tooth enamel surfacewith the photosensitizing agent, then contacting thephotosensitizer-treated tooth surface with the oxidizing compound, and,thereafter, exposing the tooth surface to light energy capable ofactivating the photosensitizer which, in turn, activates the oxidizingcompounds at the tooth enamel surface.

Another light-activated tooth whitening method, in accordance withanother embodiment of the invention includes contacting the tooth enamelsurface with an oxidizing compound which contains a photosensitizerprecursor, whereby said precursor is seen to absorb actinic radiation inthe range of 350 to 700 nm only after contact with said tooth surface.Once the photosensitizer precursor becomes light absorbent, the toothsurface is exposed to light energy capable of activating the nowabsorbent photosensitizer, which in turn activates the oxidizingcompound at the tooth surface to whiten the tooth.

A further light-activated tooth whitening method, in accordance withanother embodiment of the invention includes contacting the tooth enamelsurface with an oxidizing compound and thereafter exposing said toothenamel surface to actinic radiation corresponding to a tooth chromogenmolecule absorption wavelength. The preferred wavelengths of light inthis embodiment include those between about 350 and about 700nanometers, a more preferred embodiment include those between about 380and about 550 nanometers with the most preferred wavelengths beingbetween about 400 and about 505 nanometers. As in all of the methodsdescribed above, the oxidizing composition must be transparent to theactinic radiation utilized in order to allow the wavelength-specificlight energy to reach the tooth surface and underlying structure.

Yet another light-activated tooth whitening method, in accordance withanother embodiment of the invention includes contacting the tooth enamelsurface with a peroxyacid precursor prior to contacting said toothenamel surface with an oxidizing compound and subsequently exposing toactinic radiation as described above. The peroxyacid precursor may beplaced on the tooth surface together with or separately from aphotosensitizer.

Stained teeth may be treated individually, for instance, by directingthe light to a single tooth surface by means of a fiber optic lightguide. In this manner, several stained teeth are exposed to light insequence, the dentist or hygienist moving the light guide from tooth totooth during the procedure. This process is both labor intensive andtime consuming for the dentist or hygienist as well as tedious for thepatient. Alternatively, all of the stained teeth may be exposed to lightsimultaneously either by direct illumination from a light source shapedsubstantially like the dental arch or by indirect illumination from alight guide or device that is capable of illuminating all of the frontteeth at once.

One such device for the simultaneous and uniform illumination of atleast eight central teeth in both the upper and lower arches isillustrated in FIG. 1. This preferred embodiment has three linearoptical outputs 11, 12, and 13 precisely positioned on three front(patient facing) surfaces 1, 2, and 3. In a more preferred six barembodiment, two three bar devices are stacked one on the other resultingin six optical outputs on the front patient facing surfaces asillustrated in FIG. 2.

Although FIGS. 1 and 2 illustrate embodiments having 3 outputs and 6outputs, respectively, it is contemplated that the device may have anynumber of outputs or emitters, from one to a high multiple of outputs.Each output consisting of an individual fiber or fiber bundle thatultimately is connected to a light source. Embodiments having 3 or 6outputs are presently preferred for the device because they achievefairly uniform illumination of the eight or more central teeth withoutexcessive manufacturing problems or costs. More than six output, ofcourse are feasible and may in fact be beneficial in terms of uniformityof illumination.

The front surfaces of the device are positioned to give an outputconfiguration such that the combined beams from each optical outputconverge to illuminate at least the eight central teeth in both theupper and lower arches or the area from the incisors to the firstpre-molars in each half arch, a total area of about 10.4 cm² in theaverage male. Although depicted in FIG. 1 as linear in form, theseoutputs may be of any shape, e.g., circular, triangular or linear.Linear forms are preferred. The preferred embodiments have six linearoutputs, each output having a length to width ratio of about 16±20%—ie.,ratios of 12.8 to 19.2. In the most preferred embodiment, 80% of thelight projected from the outputs onto the 8 upper and lower centralteeth is within an area between about 0.9 and about 1.5 inches wide, theapproximate distance from the top of the enamel of the top teeth to thebottom of the enamel of the bottom teeth. Each optical output preferablyis connected to a distal light source by two glass or plastic fiberoptic bundles which originate at the distal light source, enter thedevice through a socket 20 and terminate at the trifurcated linearoutput window. Non-uniformity in fiber transmission is generallyobserved to be minor in the absence of actually breaks in the fibers.Variation in optical output from point to point at the surface of eachoutput or emitter should be no more than about ±10%.

Whether illumination of the stained teeth is performed individually oras a whole, the light emerging from a direct or indirect source may becontinuous (“on” the entire procedure), interrupted continuous (primary“on” with short rest interruptions), pulsed (“on” and “off” in apredetermined timed sequence and intensity), or a combination ofcontinuous, interrupted continuous and pulse. In a preferred embodimentfrom about 10 to about 200 milliWatt/cm² of light is appliedcontinuously to the front surface of the teeth for a total period oftime from about 10 to about 90 minutes. In a more preferred embodimentfrom about 100 to about 160 milliWatt/cm² of light is appliedcontinuously or continuously with short interruptions to the frontsurface of the teeth for a period of time from about 10 minutes to about30 minutes followed by an interruption or “off” period of about 1 to 10minutes, with the cycle repeated for a total time of approximately 40-60minutes. In one envisioned embodiment of the invention a feed-backmechanism based on reflectance would be used to monitor bleachingefficiency and regulate the total amount of actinic radiation applied.In all embodiments of the invention the positioning of the light sourceaffects the energy density applied to the teeth as power densitydecreases with distance. The preferred placement of the light sourcewill vary depending on the precise nature of the device. For the devicedescribed above, the preferred distance for placement of the device isfrom directly in front of the surface of the teeth up to about 2.0″ infront of the surface of the teeth (when measured from the middle of thelight source to the central tooth), with a distance of about 1.75″ beingmost preferred.

A number of different sources of actinic radiation have been shown tohave utility in the practice of the present invention. In general, anylight source capable of emitting actinic radiation in the wavelengthrange necessary to activate either the inventive photosensitizer(s) orotherwise raise the energy state of tooth chromogens, is contemplated tohave utility in the practice of this invention. In particular, lightsources capable of emitting actinic radiation that is both biologicallysafe and effective are preferred, especially those sources which emitlimited amounts of infrared light (700 nm and above). Infrared lightmore readily penetrates the tooth structure and may cause an excessivetemperature rise in pulpal tissue. It is preferred that light sources(combined with filters) emitting only those wavelengths necessary forthe activation of the inventive photosensitizer and/or the activation ofa tooth stain chromophores be used in the process of whitening teethwith the inventive compositions. It is generally accepted that a pulpaltemperature rise of more than 5.5° C. for a significant period of timecan be irreversibly damaging to the tooth structure.

More specifically, light sources which emit actinic radiation in thewavelength range from about 350 nanometers to about 700 nanometers areespecially preferred, in that both the photosensitivers described hereinand the tooth chromogen molecules responsible for tooth staining absorbprimarily in this region of the spectrum. Light sources which emitactinic radiation in the wavelength ranges from about 400 and about 505nanometers are most preferred. Output uniformity should be about +/−10%over the area of the beam once transmitted through a glass or plasticfiber to the optical output which may be placed in front of a patient'steeth. Although there are no limitations on the input and lengthdimensions of such a fiber, one of about 10 millimeters in diameter and3 meters in length is preferred. Such energy may be provided by a sourcewhich generates a continuous electromagnetic spectrum filtered to thepreferred wavelengths with a variation of no more than about +/−10%, orby a source which generates an emission line spectrum, or a combinationof both Suitable lamps which emit actinic radiation in the preferredrange of wavelengths include linear flash lamps, tungsten halogen, metalhalide, Xenon short arc, Mercury short arc, Mercury Xenon short arc,Argon plama arc, and Argon short arc lamps, among others. The output oftwo Mejiro BMH 250 watt metal halide lamps filtered through dichroicfilters to between about 400 and 505 nanometers meet these criteria.

The following examples set forth preferred embodiments of the invention.These embodiments are merely illustrative and are not intended to, andshould not be construed to, limit the claimed invention in any way.

EXAMPLE I

In order to determine the ability of the inventive compositions toeliminate tooth stain, a preliminary in vitro study on stained bovineenamel was performed. Squares of dental enamel 4 mm on a side were cut,using a diamond-cutting disk, from bovine permanent incisors. Using amold, the enamel squares were embedded in clear polyester casting resin(NATCOL Crafts Inc., Redlands, Calif.) to provide 1.5 cm square blockswith the labial surface exposed. The top surface of the polyester blockswas ground flush with the leveled labial surface of the enamel squaresby means of a dental model trimmer. The surface was then smoothed byhand sanding on 400-grit emery paper using water as the lubricant untilall grinding marks were removed. Finally, the top surface of the blockswas hand polished to a mirror finish using a water slurry of GK1072calcined kaolin (median particle size=1.2 microns) on a cotton cloth.The finished specimens were examined under a dissecting microscope andwere discarded if they had surface imperfections.

In preparation for the formation of artificial stained pellicle on theenamel, the specimens were etched for 60 seconds in 0.2M HCl followed bya 30-second immersion in a saturated solution of sodium carbonate. Afinal etch was performed with 1% phytic acid for 60 seconds, then thespecimens were rinsed with deionized water and attached to the stainingapparatus.

The pellicle staining apparatus was constructed to provide alternateimmersion into the staining broth and air-drying of the specimens. Theapparatus consisted of an aluminum platform base which supported aTeflon rod ( 3/4 inch in diameter) connected to an electric motor, whichby means of a speed reduction box, rotated the rod at a constant rate of1.5 rpm. Threaded screw holes were spaced at regular intervals along thelength of the rod. The tooth specimens were attached to the rod by firstgluing the head of a plastic screw to the back of a specimen. The screwis then tightened within a screw hole in the rod. Beneath the rod was aremovable, 300-ml capacity trough, which held the pellicle, stainingbroth.

The pellicle staining broth was prepared by adding 1.02 grams of instantcoffee, 1.02 grams of instant tea, and 0.75 grams of gastric mucin(Nutritional Biochemicals Corp., Cleveland Ohio 44218) to 250 ml ofsterilized trypticase soy broth. Approximately 50 ml of a 24-hourMicrococcus luteus culture was also added to the stain broth. Theapparatus, with the enamel specimens attached and the staining broth inthe trough was then placed in an incubator at 370 C. with the specimensrotating continuously through the straining broth and air. The stainingbroth was replaced once every 24 hours for ten consecutive days. Witheach broth change the trough and specimens were rinsed and brushed withdeionized water to remove any loose deposits. On the eleventh day thestaining broth as modified by the addition of 0.03 grams of FeCl₃·6H₂O,and this was continued with daily broth changes until the stainedpellicle film on the specimens was sufficiently dark. Then the specimenswere removed from the staining broth, brushed thoroughly with deionizedwater, and refrigerated in a humidor until used.

Absorbance measurements over the entire visible spectrum were obtainedusing the CIELAB color scale (Commission International de L'eclairage,Recommendations on uniform color spaces, color difference equations, andpsychometric color terms, Supplement 2 to CE publication 15 (E-13.1)1971 (TC-1.3), 1978 Paris: Beaurea Central de la CIE, 1978). The CIELABcolor scale evaluates color in terms of three axes of a color sphere,called L, a, and b. The “L” value is the axis in the color sphere whichregulates lightness and darkness on a scale from 0 (black) to 100(white). The “a” value is the axis which relates color on a yellow toblue scale, with a 0 value in the center of the sphere, positive valuestoward the yellow, and negative values toward the blue. The “b” value isthe axis which relates color on a red to green scale, with a 0 value inthe center of the sphere, positive values toward the red, and negativevalues toward the green.

The stained enamel specimens were allowed to air-dry at room temperaturefor at least one hour before absorbance measurements were made.Measurements were conducted by aligning the center of a 4-mm squaresegment of stained enamel directly over the 3-mm aperture of the Minoltaspectrophotometer. An average of 3 absorbance readings using the L*a*b*factors were taken for each specimen.

The difference between the pre-treatment (baseline) and post-treatmentreadings for each color factor (L*, a*, and b*) represented the abilityof a test solution to eliminate chromogens from the stained teeth.

The overall change in color of stained pellicle was calculated using theCIELAB equationΔE=[(ΔL*)²+(Δa*)²+(Δb*)²]^(1/2)

A “Corrected ΔE” value was calculated by eliminating from the aboveformulation the contribution of any positive Δa or Δb values (positiveΔa and Δb values are changes in tooth color in the opposite directionfrom zero, and hence construed to add color, rather than remove it).

The following oxidizing composition was prepared, which containedapproximately 15% by weight hydrogen peroxide and 0.1 percent by weightof the photosensitizer precursor 1-hydroxyethylidene-1,1-iphosphonicacid (Dequest 2010, Monsanto Corp., St. Louis, Mo.). Highly purifiedwater (18.2 megaohm, filtered through a 0.2 micron filter) was utilizedin order to maintain good stability of the composition during storage.The composition was thickened with a carboxypolymethylene polymer(Carbopol 974P, B.F. Goodrich Co., Cleveland, Ohio) to the consistencyof a light, non-runny gel. Glycerin was added in a small percentage as ahumectant and stabilizer (as a free radical scavenger), and the Carbopol974P was neutralized to a pH of 5.00 with ammonium hydroxide, resultingin the formation of a transparent and thixotropic gel. IngredientPercentage Distilled water 49.400 1-hydroxyethylidene-1,1-diphosphonicacid 1.000 Glycerin 99.7% 5.000 Hydrogen peroxide 35% 42.900 Carbopol974P 1.700 Ammonium hydroxide 29% to pH 5.5 TOTAL 100.000

The above composition was prepared in a plastic mixing chamber bycombining, under agitation with a Teflon-coated mixing paddle until aclear solution was obtained, the distilled water, the1-hydroxyethylidene-1,1-diphosphonic acid, and the glycerin. TheCarbopol 974P was then sifted slowly into the vortex created by themixing paddle and allowed to mix until a homogeneous slurry of thepolymer was obtained. Finally, the ammonium hydroxide was added in aconstant, dropwise fashion over a period of about 5 minutes untilthickening and clarification of the slurry occurred. A pH probe wasinserted periodically and the ammonium hydroxide addition proceededuntil a pH of exactly 5.00 was obtained. The resulting gel contained 15%by weight hydrogen peroxide, and was highly transparent and thixotropic(non-slumping) in character.

Each stained bovine enamel slab was coated with a 1-2 mm film of thecomposition in Example I above for a specified period of time andexposed to actinic radiation from one of several light sources. Table 1below shows some comparative results obtained by exposing gel-treatedenamel slabs to either Argon plasma arc (AR) or tungsten halogen (TH)light sources. This particular protocol called for the fiber optic lightguide to be placed 5 mm from the surface of the enamel during lightexposures. The energy of each pulse was adjusted with a power densitymeter prior to each exposure regimen and measured again after eachregimen to verify consistent output of the light source over theduration of the test. The results are listed in Table 1 below: TABLE 1Bovine Light Total Gel Number of Energy/Pulse Corrected Tooth # SourceContact Time Pulses (Joules) Delta E* B311 None 30 min  0 0.00 12.76B388 AR None 30 1.66 1.41 B277 AR 30 min  30 1.66 29.28 B214 AR 30 min 30 3.35 29.75 B283 AR 10 min  10 3.29 18.62 B147 AR 10 min  10 4.9025.98 B401 AR 10 min  30 4.97 32.18 B211 AR 5 min 15 4.84 20.05 B213 AR5 min 30 4.93 31.02 B35 TH 5 min 15 1.29 12.88 B35 TH 5 min 15 1.2919.39 B35 TH 5 min 15 1.29 20.01 B35 TH 5 min 15 1.29 23.61 B35 TH 5 min15 1.29 25.35 B35 TH 5 min 15 1.29 26.41*Elimination of positive Δa and Δb values from calculationThe data in Table 1 demonstrates that:

(1) In the in vitro model described, exposure of bovine enamel slabs,contacted with the inventive gel composition above, to pulsed actinicradiation from a Argon plasma arc light source resulted in significantlyreduced tooth stain as compared to slabs treated either with just gelalone (and not exposed to the light source) or light source exposureonly (no gel).

(2) Six sequential treatments (over 30 minutes) of a single stainedbovine enamel slab (B35) with gel and concurrent exposure of said slabto pulsed actinic radiation from a tungsten halogen light source (5minute exposure periods) resulted in an increasing level of tooth stainremoval over the period of the test. The result was significantlylighter in color than that achieved in tooth number B311, which was alsoin contact with the inventive gel composition, but did not get exposedto a light source.

EXAMPLE II

A comparative study of light transmission through various light and/orheat activated tooth whitening gels was undertaken. Spectral energycurves were generated using an Ocean Optics spectrometer with a 50micron fiber for gather emission data Light transmission through a glassmicroscope slide was used as a control and the test consisted of coatingthe slide with a 1-2 mm thick layer of each tooth whitening gel andilluminating with a metal halide light source connected to an 8 mm glassfiber optic light guide. The light was filtered through a 505 nm shortpass filter (only wavelengths less than 505 nm pass through) prior toentering the light guide. The spectrometer's fiber optic probe wasplaced against the opposite side of the slide from the gel in order todetect the wavelengths of light allowed to pass through the gel on theslide. The spectral curves of FIGS. 4 A-E clearly demonstrate the degreeof light attenuation caused by all of the commercially availablecompositions: FIG. 4A-Control; FIG. 4B-Inventive Example I; FIG.4C-Shofu Hi-Lite; FIG. 4D-QuasarBrite; Figure E-Opalescence Xtra

The attenuation of power density, measured in mW/cm², was determined forthe same four compositions by again placing a 1-2 mm layer of each gelor paste on a glass microscope slide and placing the slide/gel assemblyin the path between the light source and the detector well of the powerdensity meter. Due to the depth and shape of the detector well, theslide was 7 mm above the actual detector surface, rather than directlyin contact with it. The power density was recorded at the beginning (B)and at the end of a 60 minute light exposure (E). The power densitywithout slide or gel in the light path was adjusted to 175 mW/m²: Theresults are shown in Table 2 below. TABLE 2 Energy Density CompositionU.S. Pat. No. (m W/cm²) Control (slide only) — 165 Example I (B) + (E) —160 & So Shofu Hi-Lite (B) 5,032,178 25 Shofu Hi-Lite (E) 5,032,178 50QuasarBrite (B) 5,240,415 110 QuasarBrite (E) 5,249,415 111 OpalescenceXtra (B) 5,785,527 65 Opalescence Xtra (E) 5,785,527 94

EXAMPLE III

Another transparent hydrogen peroxide gel was prepared that had a lowerconcentration of oxidizer (3% by weight of H₂O₂), but at a pH of 7.0 anda much higher viscosity (approximately 1,000,000 cps). The gel below wasprepared in accordance with the procedure in Example I, except that aKynar coated Ross Double Planetary vacuum mixer (Charles Ross & Sons,Haupaugge, N.Y.) was used to handle the elevated viscosity achievedduring and after neutralition with the ammonium hydroxide. Sodiumstannate was added as an additional stabilizer for the hydrogenperoxide. Ingredient Percentage Distilled water 81.010 Glycerin 99.7%5.000 1-hydroxyethylidene-1,1-diphosphonic acid 0.400 Sodium stannate0.015 Hydrogen peroxide 35% 8.570 Carbopol 974P 5.000 Ammonium hydroxide29% to pH 7.0 TOTAL 100.000

The ability of the 3% hydrogen peroxide gel, transparent to visiblelight between the wavelengths of 380 and 700 nanometers, is demonstratedin Table 3 below. TABLE 3 Wavelength Power Energy/ Bovine Oxidizing TimeLight Range Pulses/ Density Pulse Tooth # Gel Period Source (nanometers)Period (mW/cm2) (Joules) Delta E* B388 Example II 5 min AR 380-505 154.84 19.67 B388 Example II 5 min AR 380-505 15 4.84 29.43 B388 ExampleII 5 min AR 380-505 15 4.84 32.74 B365 Example II 5 min None — 0 0 3.41B365 Example II 5 min None — 0 0 4.23 B365 Example II 5 min None — 0 05.78 B365 Example II 5 min AR 380-505 15 4.84 23.49 B365 Example II 5min AR 380-505 15 4.84 30.27 B367 Example I 30 min  TH 400-520Continuous 250 32.26*Elimination of positive Δa and Δb values from calculation.

EXAMPLE IV

Extracted human teeth (HE) that were non-carious and free of amalgam orresin-based restorative materials were utilized to study the ability ofthe inventive compositions to eliminate the stains from human enamel anddentin. The teeth were coated with a 1-2 mm thick film of an oxidizinggel and irradiated according to the regimens shown in Table IV below.The resulting change in tooth color (Δ Shades) was recorded as thenumber of VITA® shade difference between the original baseline VITA®shade value and the final VITA® shade value. TABLE 4 Light ExposurePulses/ Joules/ Shade Shade Δ Tooth # Gel Source Time (min) Minute Pulse(Initial) (Final) Shade HE2 Example I AR 30 1 4.84 B4 C2 6 HE3 Example IAR 30 1 4.84 A4 A3.5 3 HE4 Example I AR 30 1 4.84 A3 B2 6 HE5 Example IAR 30 1 4.84 B3 D4 3 HE6 Example I AR 30 1 4.84 B3 B2 8 HE7 Example I AR30 1 4.84 A3 A1 7 HE8 Exampie I AR 30 1 4.84 A3.5 A2 7 HE9 Example I AR30 1 4.84 A3 A1 7 HE10 Example I AR 30 1 4.84 A4 A3.5 6 HE11 Example IAR 30 1 4.84 A3.5 A2 7 HE12 Example I AR 30 2 4.84 A3.5 A2 7 HE13Example I AR 30 2 4.84 B3 B2 8 HE14 Example I AR 30 2 4.84 A3.5 B2 9HE15 Example I AR 30 2 4.84 A4 A1 13 HE16 Example I AR 30 2 4.84 B4 B112 HE17 Example I AR 30 1 1.64 A3 A2 4 HE18 Example I AR 30 1 1.64 B4 B210 HE19 Example I AR 30 1 1.64 C4 D3 6 HE20 Example I AR 30 1 1.64 B3 A26 HE21 Example I AR 30 1 1.64 B3 B2 8 HE22 Example I No light 30 0 0 B3A2 2 HE23 Example I No light 30 0 0 A3 A2 4 HE24 Example I No light 30 00 B3 D4 3 HE25 Example I No light 30 0 0 D3 B2 7 HE26 Example I No light30 0 0 B3 A2 6 HE27 Example I Tungsten 60 Continuous 250 B3 A1 9 HalogenmW/cm2

EXAMPLE V

Human extracted teeth were whitened as follows by applying a 1-2 mmthick film of gel on the enamel surface and exposing the same surface tovarying power densities from a metal halide light source with a 505 nmshort pass internal filter. Comparisons were done to two controls, oneof which was Gel exposure only (no light) and light exposure only (noGel). Exposure regimens, consisting of gel application (except in thecase of light only/no Gel), followed by 20 minutes of continuous lightexposure, were repeated three times (3×20 minutes). TABLE 5 Power LightDensity Test Initial Final Shade Tooth # Gel Source (mW/cm2) FilterDuration Shade Shade Change HE101 Example I MH 250 505 3 × 20 min A3.5A1 7 HE102 Example I MH 250 505 3 × 20 min B4 A2 8 HE103 Example I MH175 505 3 × 20 min A3 B1+ 8 HE104 Example I MH 175 505 3 × 20 min A4 B212 HE105 Example I MH 175 505 3 × 20 min B3 B2 8 HE106 Example I MH 175505 3 × 20 min A3 B1+ 8 HE107 Example I MH 175 505 3 × 20 min A4 A2 10HE108 Example I No light 3 × 20 min A3.5 A3 3 HE109 Example I No light 3× 20 min A4 D3 5 HE110 Example I No light 3 × 20 min A3.5 A3.5 0 HE111Example I No light 3 × 20 min A4 A3 6 HE112 Example I No light 3 × 20min A4 A3.5 3 HE113 None MH 175 505 3 × 20 min A3 A3 0 HE114 None MH 175505 3 × 20 min A4 A4 0 HE115 None MH 175 505 3 × 20 min A3.5 A3 3 HE116None MH 175 505 3 × 20 min B3 B3 0

EXAMPLE VI

A pulpal chamber of an endo-tooth in a cooperative and informed patientwas wired using a thermal probe and thermo-conducting paste. Pulpaltemperatures were measuring during an actual whitening procedure, inwhich the illumination was supplied using the currently available UnionBroach Mumunator and the device described in the instant applicationused at the most preferred wavelengths of 400 to 505 nanometers.Measurements of the energy densities at the tooth surface showedcomparable energy densities for each device (230 milliwatts/cm² for theUnion Broach Illuminator and 200 milliwatts/cm² for the device describedin the instant application, respectively). The results are shown belowin Table 6.

Illumination using the device described in the instant application inthe preferred wavelength range from about 400 to 505 nanometers raisedpulpal chamber temperature less than did the Union Broach device. Inthis experiment, temperatures rose to a maximum by twenty minutes andwere then stable. In contrast to the temperature rise seen with theUnion Broach device, at no time did the temperature using the devicedisclosed in the instant application rise above the 5.5° C. which couldresult in thermally induced pulpitis if maintained for a significantperiod of time. The temperature changes seen are likely to be greaterthan those seen with vital teeth as endo-teeth have no blood supply toprovide additional cooling. Time Temperature Rise (deg. C. from ambient)(min.) Union Broach BriteSmile 2000 5 4 2.9 10 8 4.5 15 9 5.3 20 9 4.225 9.5 4.5 30 9 4.3

Upon reading the subject application, various alternative constructionsand embodiments will become obvious to those skilled in the art. Thesevariations are to be considered within the scope and spirit of thesubject invention. The subject invention is only to be limited by theclaims which follow and their equivalents.

1-24. (canceled)
 25. A method of whitening teeth comprising the stepsof: contacting a stained tooth surface with an organic metal-ligandcomplex and an oxidizing compound; and exposing the stained toothsurface to actinic radiation.
 26. The method of claim 25, wherein theorganic metal-ligand complex comprises iron, copper or manganese. 27.The method of claim 25, wherein the organic metal-ligand complexcomprises an oxalate, gluconate, or bis-phosphonate ligand.
 28. Themethod of claim 25, wherein the actinic radiation has a wavelengthbetween about 350 and about 700 nanometers.
 29. The method of claim 25,wherein the actinic radiation has a wavelength between about 350 andabout 500 nanometers.
 30. The method of claim 25, wherein the actinicradiation has a wavelength between about 380 and about 505 nanometers.31. The method of claim 25, wherein the actinic radiation has awavelength between about 400 and about 500 nanometers.
 32. The method ofclaim 25, wherein the oxidizing compound is hydrogen peroxide.
 33. Themethod of claim 25, wherein the oxidizing compound is an alkali metalpercarbonate.
 34. The method of claim 25, wherein the oxidizing compoundis carbamide peroxide.
 35. The method of claim 25, wherein the oxidizingcompound is a peroxacid.
 36. The method of claim 25, wherein the actinicenergy has a power density between about 10 and about 200 mW/cm² at thestained tooth surface.
 37. The method of claim 25, wherein the stainedtooth surface is exposed to actinic radiation for a period of timebetween about 10 and about 90 minutes.